Characteristics of SUS 3O4/Ni-P alloy composite coatings sprayed on carbon steel substaretes were investigated by X-ray dffraction, EPMA analysis, hardness test, wear test and adhesion test between substrate and coating. And also interface structure between substrate and coating and or sprash particles west investigated by TEM observation. The obtained results are as follows.(1) Sprayed coatings consist of mixture of SUS3O4 splashes and Ni-P alloy splashes.(2) It can be seen from TEM diffraction pattern that a part of Ni-P alloy splashes are amorphized.(3) Hardness of composite coating increases with increasing Ni-P alloy content(4) Wear loss of composite coatings shows minimum in the range between 60 and 8O vol%Ni-P alloy content(5) Surface of coatings are smooth wity increasing Ni-P alloy content, while surface roughness is low.(6) 6Ovol%Ni-P alloy coating shows maximum adhesion strength between substrate and coaling.(7) All of the SUS 3O4/Ni-P alloy composite coalnigs are attackedin l0% HCl solution. Bad corrosion resistance is due to presence of pores and cracks in coatings.(8) Specimens for TEM observation can be made. But, interface between substrate and coating and or splashes were not distinguished.